Silver colored coated article with low-E coating having absorber layer and low visible transmission

ABSTRACT

A low-emissivity (low-E) coating on a substrate (e.g., glass substrate) includes at least first and second infrared (IR) reflecting layers (e.g., silver based layers) that are spaced apart by contact layers (e.g., NiCr based layers), a layer comprising silicon nitride, and an absorber layer of or including a material such as niobium zirconium which may be oxided and/or nitrided. The absorber layer is designed to allow the coated article to realize glass side reflective (equivalent to exterior reflective in an IG window unit when the coating is provided on surface #2 of an IG window unit) silver color. In certain example embodiments, the coated article (monolithic form and/or in IG window unit form) has a low visible transmission (e.g., from 15-45%, more preferably from 22-39%, and most preferably from 24-35%). In certain example embodiments, the coated article may be heat treated (e.g., thermally tempered and/or heat bent).

This application is the U.S. national phase of International ApplicationNo. PCT/US2016/057439 filed Oct. 18, 2016, the entire content of whichis hereby incorporated by reference in this application.

This invention relates to a coated article including a low-emissivity(low-E) coating. In certain example embodiments, the low-E coating isprovided on a substrate (e.g., glass substrate) and includes at leastfirst and second infrared (IR) reflecting layers (e.g., silver basedlayers) that are spaced apart by contact layers (e.g., NiCr basedlayers), a layer comprising silicon nitride, and an absorber layer of orincluding a material such as niobium zirconium which may be oxidedand/or nitrided. The absorber layer is designed to allow the coatedarticle to realize glass side/exterior reflective silver color. Incertain example embodiments, the coated article (monolithic form and/orin IG window unit form) has a low visible transmission (e.g., from15-45%, more preferably from 22-39%, and most preferably from 24-35%).In certain example embodiments, the coated article may be heat treated(e.g., thermally tempered and/or heat bent). Coated articles accordingto certain example embodiments of this invention may be used in thecontext of insulating glass (IG) window units, vehicle windows, othertypes of windows, or in any other suitable application.

BACKGROUND OF THE INVENTION

Coated articles are known in the art for use in window applications suchas insulating glass (IG) window units, vehicle windows, and/or the like.It is known that in certain instances, it is desirable to heat treat(e.g., thermally temper, heat bend and/or heat strengthen) such coatedarticles for purposes of tempering, bending, or the like. Heat treatment(HT) of coated articles typically requires use of temperature(s) of atleast 580 degrees C., more preferably of at least about 600 degrees C.and still more preferably of at least 620 degrees C. Such hightemperatures (e.g., for 5-10 minutes or more) often cause coatings tobreak down and/or deteriorate or change in an unpredictable manner.Thus, it is desirable for coatings to be able to withstand such heattreatments (e.g., thermal tempering), if desired, in a predictablemanner that does not significantly damage the coating.

In certain situations, designers of coated articles strive for acombination of desirable visible transmission, desirable color, lowemissivity (or emittance), and low sheet resistance (R_(s)).Low-emissivity (low-E) and low sheet resistance characteristics permitsuch coated articles to block significant amounts of IR radiation so asto reduce for example undesirable heating of vehicle or buildinginteriors.

Silver coloration is sometimes desired in the context of monolithicwindows, insulating glass (IG) window units, and/or other suitableapplications. Desirable silver coloration (e.g., glass side reflective,or exterior), measured monolithically and/or in an IG window unit, maybe characterized by: high glass side visible reflectance of from 23-43%,more preferably from 25-40%, and most preferably from 27-35%, glass sidereflective a* color values of from −6.0 to +5.0, more preferably from−3.5 to +4.0, and most preferably −2.5 to +3.0; in combination withglass side reflective b* color values of from −11.0 to +3.0, morepreferably from −9.0 to +1.0, and most preferably from −8.0 to −1.0; anda visible transmission (TY or T_(vis)) of from 15-45%, more preferablyfrom 22-39%, and most preferably from 24-35%. Note that optical values(e.g., a*, b*, T_(vis), R_(GY), R_(FILM)) herein are measured inaccordance with the Illuminant C, 2 degree, standard.

It has been difficult to achieve desirable silver glass side reflectivecoloration in combination with acceptable solar values such as low sheetresistance, SF, and/or SHGC.

Low solar factor (SF) and solar heat gain coefficient (SHGC) values aredesired in some applications, particularly in warm weather climates.Solar factor (SF), calculated in accordance with EN standard 410,relates to a ratio between the total energy entering a room or the likethrough a glazing and the incident solar energy. Thus, it will beappreciated that lower SF values are indicative of good solar protectionagainst undesirable heating of rooms or the like protected bywindows/glazings. A low SF value is indicative of a coated article(e.g., IG window unit) that is capable of keeping a room fairly cool insummertime months during hot ambient conditions. Thus, low SF values aresometimes desirable in hot environments. While low SF values aresometimes desirable for coated articles such as IG window units, theachievement of lower SF values may come at the expense of sacrificingcoloration. It is often desirable, but difficult, to achieve acombination of acceptable visible transmission, desirable glass sidereflective coloration, and a low SF value for a coated article such asan IG window unit or the like. SF (G-Factor; EN410-673 2011) and SHGC(NFRC-2001) values are calculated from the full spectrum (T, Rg and Rf)and are typically measured with a spectrophotometer such as a PerkinElmer 1050. The SF measurements are done on monolithic coated glass, andthe calculated values can be applied to monolithic, IG and laminatedapplications.

U.S. Patent Document 2012/0177899 discloses several different coatings.The Examples 1, 4 and 5 on page four of US '899 in [0026] areglass/SiN/NiCrNx/SiN/NiCrNx/SiN. However, these examples haveundesirably high sheet resistance values of from 40-75 ohms/square, andundesirable green or bronze glass side reflective coloration.Unfortunately, all Examples in US '899 suffer from undesirably highsheet resistance values of from 40-75 ohms/square, and undesirably highSF and SHGC values.

U.S. Pat. No. 5,557,462 discloses a low-E coating with a layer stack ofSiN/NiCr/Ag/NiCr/SiN/NiCr/Ag/NiCr/SiN. However, the coated article ofthe '462 patent has an undesirably high visible transmission of at least63%, and a low glass side/exterior reflectance (R_(G)Y) of less thanabout 10% which is too low to realize desirable silver coloration. The'462 patent at column 3, lines 12-15, teaches that visible transmissionbelow 70% (monolithic coated article) and below 63% (IG window unit) areundesirable. Thus, the '462 patent teaches directly away from coatedarticles with visible transmission lower than 63%. Moreover, as largelyexplained in U.S. Pat. No. 8,173,263, coated articles of the '462 patentare not reasonably heat treatable at least because upon heat treatmentsheet resistance (R_(s)) goes way up such as from about 3-5 to well over10.

U.S. Patent Document 2016/0185660 discloses a low-E coating with a layerstack of SiN/NiCr/Ag/NiCr/SiN/NiCr/Ag/NiCr/SiN/ZrO. However, it has beenfound here that durability of this layer stack can be improved upon.Moreover, the example coated articles described in the '660 patent,namely Examples 1-3, have undesirably high visible transmissions of over47%, and cannot realize desirable silver glass side/exterior coloration.For instance, the glass side/exterior visible reflectance values(R_(G)Y) of Examples 1-3 in the '660 patent document are from 8-12%which way too low to allow the coated articles to realize desirablesilver glass side/exterior coloration. Thus, there is room forimprovement regarding the '660 patent document with respect to one ormore of durability, visible transmission, coloration, and/or glass sidevisible reflectance.

Thus, it would be desirable if silver glass side reflective colorationcould be achieved, measured monolithically and/or in an IG window unit,in combination with good durability, low sheet resistance, low visibletransmission, and low SF and/or SHGC value(s). Note that a typicalconventional IG window unit with two panes has an SHGC value around0.70.

BRIEF SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

Example embodiments of this invention relate to a coated articleincluding a low-emissivity (low-E) coating. In certain exampleembodiments, the low-E coating is provided on a substrate (e.g., glasssubstrate) and includes at least first and second infrared (IR)reflecting layers (e.g., silver based layers) that are spaced apart bycontact layers (e.g., NiCr based layers) and a dielectric layer of orincluding a material such as silicon nitride and an absorber layer of orincluding a material such as niobium zirconium which may be oxided(e.g., NbZrO_(x)) and/or nitrided (e.g., NbZrO_(x)N_(y)). The additionof the absorber layer, which if oxided is preferably sub-oxided(partially oxided) and which if nitrided is preferably sub-nitrided(partially nitrided with fairly small amounts of nitrogen), has beenfound to increase durability and can be utilized to provide desirablesilver glass side/exterior reflective coloration including high glassside visible reflectance, low visible transmission, desirabletransmissive color and more desirable film side reflective b* values,and low SF and SHGC value(s). In certain example embodiments, the coatedarticle (monolithic form and/or in IG window unit form) has silver glassside reflective visible coloration and a low visible transmission (e.g.,from 15-45%, more preferably from 22-39%, and most preferably from24-35%). In certain example embodiments, the coated article may be heattreated (e.g., thermally tempered and/or heat bent). Coated articlesaccording to certain example embodiments of this invention may be usedin the context of insulating glass (IG) window units, vehicle windows,other types of windows, or in any other suitable application.

In certain example embodiments of this invention, there is provided acoated article including a coating supported by a glass substrate andhaving silver glass side reflective color, the coating comprising: firstand second infrared (IR) reflecting layers comprising silver, the firstIR reflecting layer being located closer to the glass substrate than isthe second IR reflecting layer; a first contact layer located over anddirectly contacting the first IR reflecting layer comprising silver; adielectric layer comprising silicon nitride located over and directlycontacting the first contact layer; wherein the dielectric layercomprising silicon nitride is split by a splitting absorber layercomprising Nb and Zr, so that the splitting absorber layer comprising Nband Zr is located between and contacting a first portion of thedielectric layer comprising silicon nitride and a second portion of thedielectric layer comprising silicon nitride; a second contact layerlocated over the layer comprising silicon nitride; the second IRreflecting layer comprising silver located over and directly contactingthe second contact layer; a third contact layer located over anddirectly contacting the second IR reflecting layer; another dielectriclayer comprising silicon nitride located over the third contact layer;and wherein the coated article has a visible transmission of from15-45%, a glass side visible reflectance of from 23-43%, a glass sidereflective a* value from −6.0 to +5.0, and a glass side reflective b*value from −11.0 to +3.0.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a coated article according to anexample embodiment of this invention.

FIG. 2 is a cross sectional view showing the coated article of FIG. 1provided in an IG window unit according to an example embodiment of thisinvention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Coated articles herein may be used in applications such as IG windowunits, laminated window units (e.g., for use in vehicle or buildingapplications), vehicle windows, monolithic architectural windows,residential windows, and/or any other suitable application that includessingle or multiple glass substrates.

Certain embodiments of this invention relate to a coated articleincluding a low-emissivity (low-E) coating 30. In certain exampleembodiments, the low-E coating 30 is provided on (directly orindirectly) a substrate (e.g., glass substrate) 1 and includes at leastfirst and second infrared (IR) reflecting layers (e.g., silver basedlayers) 9, 19 that are spaced apart by contact layers (e.g., NiCr basedlayers) 11, 17 and a dielectric layer 14 of or including a material suchas silicon nitride and an absorber layer 15 of or including a materialsuch as niobium zirconium which may be oxided (e.g., NbZrO_(x)) and/ornitrided (e.g., NbZrO_(x)N_(y)) in a substoichiometric manner. Theaddition of the absorber layer 15, which if oxided is preferablysub-oxided (partially oxided) and which if nitrided is preferablysub-nitrided (partially nitrided with fairly small amounts of nitrogen),has been found to increase durability and can be utilized to providedesirable silver glass side/exterior reflective coloration includinghigh glass side visible reflectance, low visible transmission, desirabletransmissive color and more desirable film side reflective b* values,and low SF and SHGC value(s). Thus, the absorber layer 15 has been foundto advantageously provide acceptable thermal performance in combinationwith desirable indoor and outdoor transmissive and/or reflectivecoloration. In certain example embodiments, the coated article(monolithic form and/or in IG window unit form) has a low visibletransmission (e.g., from 15-45%, more preferably from 22-39%, and mostpreferably from 24-35%). In certain example embodiments, the coatedarticle may be heat treated (e.g., thermally tempered and/or heat bent).In example embodiments of this invention, the coated article, if aninsulating glass (IG) window unit having two glass substrates, has an SFvalue of no greater than 0.27 (more preferably no greater than 0.25, andmost preferably no greater than 0.21) and/or an SHGC value of no greaterthan 0.27 (more preferably no greater than 0.25, and most preferably nogreater than 0.23 or 0.20). Thus, such coatings provide for improvedcolor control and/or ranges when desired, good durability and desirablevisible transmission values, and desirable low SF and/or SHGC valuesindicating ability to keep rooms cool in warm environments.

The terms “heat treatment” and “heat treating” as used herein meanheating the article to a temperature sufficient to achieve thermaltempering, heat bending, and/or heat strengthening of the glassinclusive article. This definition includes, for example, heating acoated article in an oven or furnace at a temperature of least about 580degrees C., more preferably at least about 600 degrees C., for asufficient period to allow tempering, bending, and/or heatstrengthening. In certain instances, the HT may be for at least about 4or 5 minutes. The coated article may or may not be heat treated indifferent embodiments of this invention.

In certain example embodiments of this invention, the coating includes adouble-silver stack. Referring to FIG. 1 for example, in certain exampleembodiments of this invention, there is provided a coated articleincluding a coating supported by a glass substrate, the coatingcomprising: first 9 and second 19 infrared (IR) reflecting layerscomprising or consisting essentially of silver, the first IR reflectinglayer 9 being located closer to the glass substrate 1 than is the secondIR reflecting layer 19; a first contact layer comprising NiCr 7 locatedunder and directly contacting the first IR reflecting layer comprisingsilver 9, a second contact layer 11 located over and directly contactingthe first IR reflecting layer comprising silver 9; a dielectric layercomprising silicon nitride 14 (the layer 14 is made up of lower layerportion 14 a and upper layer portion 14 b) located over and directlycontacting the first contact layer comprising NiCr 11; wherein thedielectric layer comprising silicon nitride 14 is split by an absorbinglayer 15 of or including niobium zirconium which may be sub-oxidedand/or nitrided, so that the absorbing layer 15 is located between andcontacting lower portion 14 a of the dielectric layer comprising siliconnitride and upper portion 14 b of the dielectric layer comprisingsilicon nitride; a third contact layer comprising NiCr 17 located overand directly contacting the upper portion 14 b of the layer comprisingsilicon nitride 14; the second IR reflecting layer comprising silver 19located over and directly contacting the second contact layer comprisingNiCr 17; a fourth contact layer comprising NiCr 21 located over anddirectly contacting the second IR reflecting layer 19. The lower IRreflecting layer 9 is at least 20 angstroms thicker, more preferably atleast 40 angstroms thicker, than is the upper IR reflecting layer 19 incertain example embodiments, as this has been found to allow the glassside visible reflectance to be increased to help achieve silver glassside reflective coloration in combination with low visible transmission.The provision of the absorbing layer 15, splitting the silicon nitridebased layer 14 into two equal or unequal portions, has also been foundto improve durability. The coating 30 may include three dielectriclayers 3, 14 and 24 of or including silicon nitride, as shown in FIG. 1.Moreover, the coating 30 may include a layer (e.g., overcoat) 27 of orincluding zirconium oxide and/or zirconium oxynitride in certain exampleembodiments. In certain example embodiments, this overcoat layer of orincluding zirconium oxide and/or zirconium oxynitride 27 is thinner thanone or both of the IR reflecting layers 9, 19 comprising silver in thecoating. In certain example embodiments of this invention, each of theIR reflecting layers comprising silver 9 and 19 is at least twice asthick, and more preferably at least three times as thick, as the layer27 or including zirconium oxide and/or zirconium oxynitride. In certainexample embodiments of this invention, the coating includes only two IRreflecting layers 9, 19 of or including silver or the like.

In order to increase durability and to provide for desirable silverglass side/exterior coloration in combination with low sheet resistanceand desirable optical/solar features, along with optics and thermalproperties, coated articles according to certain example embodiments ofthis invention have a center dielectric layer 14 of or including siliconnitride split by the niobium zirconium inclusive absorber layer 15, andlower contact layers 7, 17 may be based on NiCr (as opposed to ZnO). Ithas also been found that using metallic or substantially metallic NiCr(possibly partly nitrided) for layer(s) 7, 11, 17 and/or 21 improveschemical, mechanical and environmental durability (compared to using ZnOlower contact layers below silver and/or highly oxided NiCr uppercontact layers above silver). However, ZnO may still be used inalternative embodiments. It has also been found that sputter-depositingsilicon nitride inclusive layer 14 in an amorphous state, so that it isamorphous in both as-coated and HT states, helps with overall stabilityof the coating. For example, 5% HCl at 65 degrees C. for one hour willremove the coating of U.S. Pat. No. 7,521,096, whereas the coating shownin FIG. 1 and the examples herein can survive this HCl test. And in hightemperature and high humidity environment, there is less damage to thecoating of FIG. 1 and the examples herein after ten days of exposure,than to the coating of the '096 patent after two days of exposure. Andregarding high corrosive chemicals such as those used for “brick wash”,corrosion resistance is such that edge deletion need not be performed incertain example IG and laminated embodiments. Similarly, for mechanicalabrasion tests, thermal cycling and salt fog tests, the coatings of theexamples herein were found to be better than that of the '096 patent.

In certain example embodiments of this invention such as FIG. 1, heattreated or non-heat-treated coated articles having multiple IRreflecting layers (e.g., two spaced apart silver based layers) arecapable of realizing a sheet resistance (R_(s)) of less than or equal to6.0 (more preferably less than or equal to 5.0, even more preferablyless than or equal to 4.0). The terms “heat treatment” and “heattreating” as used herein mean heating the article to a temperaturesufficient to achieve thermal tempering, heat bending, and/or heatstrengthening of the glass inclusive article. This definition includes,for example, heating a coated article in an oven or furnace at atemperature of least about 580 degrees C., more preferably at leastabout 600 degrees C., for a sufficient period to allow tempering,bending, and/or heat strengthening. In certain instances, the HT may befor at least about 4 or 5 minutes. The coated article may or may not beheat treated in different embodiments of this invention.

FIG. 1 is a side cross sectional view of a coated article according toan example non-limiting embodiment of this invention. The coated articleincludes substrate 1 (e.g., clear, green, bronze, or blue-green glasssubstrate from about 1.0 to 10.0 mm thick, more preferably from about1.0 mm to 6.0 mm thick), and low-E coating (or layer system) 30 providedon the substrate 1 either directly or indirectly. The coating (or layersystem) 30 includes, for example: bottom dielectric silicon nitridelayer 3 which may be Si₃N₄, or of the Si-rich type silicon nitride forhaze reduction, or of any other suitable stoichiometry silicon nitridein different embodiments of this invention, lower contact layer 7 (whichcontacts bottom IR reflecting layer 9), first conductive and preferablymetallic or substantially metallic infrared (IR) reflecting layer 9,upper contact layer 11 (which contacts IR reflecting layer 9),dielectric silicon nitride based and/or inclusive layer 14 split intotwo portions 14 a, 14 b by absorber layer 15, lower contact layer 17(which contacts IR reflecting layer 19), second conductive andpreferably metallic or substantially metallic IR reflecting layer 19,upper contact layer 21 (which contacts layer 19), dielectric siliconnitride layer 24 which may be Si₃N₄, of the Si-rich type for hazereduction, or of any other suitable stoichiometry silicon nitride indifferent embodiments of this invention, and overcoat layer 27 of orincluding a material such as zirconium oxide (e.g., ZrO₂) and/orzirconium oxynitride. The “contact” layers 7, 11, 17 and 21 each contactan IR reflecting layer (e.g., layer based on Ag). The aforesaid layers3-27 make up low-E (i.e., low emissivity) coating 30 that is provided onglass or plastic substrate 1. Layers 3-27 may be sputter-deposited onthe substrate 1 in certain example embodiments of this invention, witheach layer being sputter-deposited in vacuum using one or more targetsas needed (the sputtering targets may be ceramic or metallic). Metallicor substantially metallic layers (e.g., layers 7, 9, 11, 17, 19 and 21)may be sputtered in an atmosphere containing argon gas, whereas nitridedlayers (e.g., layers 3, 7, 11, 14, 17, 21 and/or 24) may be sputtered inan atmosphere containing a mixture of nitrogen and argon gas. Absorberlayer 15 is preferably sputter-deposited from an NbZr target(s) in anatmosphere having a mixture of argon (Ar) and a small amount of oxygen(and possibly) nitrogen gas(es). As indicated above, the contact layers7, 11, 17 and 21 may or may not be nitrided in different exampleembodiments of this invention.

In monolithic instances, the coated article includes only one glasssubstrate 1 as illustrated in FIG. 1. However, monolithic coatedarticles herein may be used in devices such as laminated vehiclewindshields, IG window units, and the like. As for IG window units, anIG window unit may include two spaced apart glass substrates. An exampleIG window unit is illustrated and described, for example, in U.S. PatentDocument No. 2004/0005467, the disclosure of which is herebyincorporated herein by reference. FIG. 2 shows an example IG window unitincluding the coated glass substrate 1 shown in FIG. 1 coupled toanother glass substrate 2 via spacer(s), sealant(s) 40 or the like, witha gap being defined therebetween. This gap between the substrates in IGwindow unit embodiments may in certain instances be filled with a gassuch as argon (Ar). An example IG unit may comprise a pair of spacedapart clear glass substrates, which may be matte glass substrates incertain example instances, each about 3-7 mm (e.g., 6 mm) thick, one ofwhich is coated with a coating 30 herein in certain example instances,where the gap between the substrates may be from about 5 to 30 mm, morepreferably from about 10 to 20 mm, and most preferably about 16 mm. Incertain example instances, the low-E coating 30 may be provided on theinterior surface of either substrate facing the gap (the coating isshown on the interior major surface of substrate 1 in FIG. 2 facing thegap, but instead could be on the interior major surface of substrate 2facing the gap). Either substrate 1 or substrate 2 may be the outermostsubstrate of the IG window unit at the building exterior (e.g., in FIG.2 the substrate 1 is the substrate closest to the building exterior, andthe coating 30 is provided on surface #2 of the IG window unit). WhileFIG. 2 shows the coating 30 on surface #2 of the IG window unit (so thatglass side reflective color is viewed from the exterior of thebuilding), it is possible that the coating 30 may be provided on surface#3 of the IG window unit in alterative embodiments in which case glassside reflective color would be as viewed from the interior of thebuilding.

In certain example embodiments of this invention, one, two, three, orall four of contact layers 7, 11, 17, 21 may be of or include NiCr (anysuitable ratio of Ni:Cr), and may or may not be nitrided (NiCrNx). Incertain example embodiments, one, two, three or all four of these NiCrinclusive layers 7, 11, 17, 21 is substantially or entirelynon-oxidized. In certain example embodiments, layers 7, 11, 17 and 21may all be of metallic NiCr or substantially metallic NiCr (althoughtrace amounts of other elements may be present). In certain exampleembodiments, one, two, three or all four of NiCr based layers 7, 11, 17,21 may comprise from 0-10% oxygen, more preferably from 0-5% oxygen, andmost preferably from 0-2% oxygen (atomic %). In certain exampleembodiments, one, two, three or all four of these layers 7, 11, 17, 21may contain from 0-20% nitrogen, more preferably from 1-15% nitrogen,and most preferably from about 1-12% nitrogen (atomic %). NiCr basedlayers 7, 11, 17 and/or 21 may or may not be doped with othermaterial(s) such as stainless steel, Mo, or the like. It has been foundthat the use of NiCr based contact layer(s) 7 and/or 17 under thesilver-based IR reflecting layer(s) 9, 19 improves durability of thecoated article (compared to if layers 7 and 17 were instead of ZnO).

Dielectric layers 3, 14 (including 14 a and 14 b), and 24 may be of orinclude silicon nitride in certain embodiments of this invention.Silicon nitride layers 3, 14 and 24 may, among other things, improveheat-treatability of the coated articles and protect the other layersduring optional HT, e.g., such as thermal tempering or the like. One ormore of the silicon nitride layers 3, 14, 24 may be of thestoichiometric type (i.e., Si₃N₄), or alternatively of the Si-rich typeof silicon nitride in different embodiments of this invention. Thepresence of free Si in a Si-rich silicon nitride inclusive layer 3and/or 14 may, for example, allow certain atoms such as sodium (Na)which migrate outwardly from the glass 1 during HT to be moreefficiently stopped by the Si-rich silicon nitride inclusive layer(s)before they can reach silver and damage the same. Thus, it is believedthat the Si-rich Si_(x)N_(y) can reduce the amount of damage done to thesilver layer(s) during HT in certain example embodiments of thisinvention thereby allowing sheet resistance (R_(s)) to decrease orremain about the same in a satisfactory manner. Moreover, it is believedthat the Si-rich Si_(x)N_(y) in layers 3, 14 and/or 24 can reduce theamount of damage (e.g., oxidation) done to the silver and/or NiCr duringHT in certain example optional embodiments of this invention. In certainexample embodiments, when Si-rich silicon nitride is used, the Si-richsilicon nitride layer (3, 14 and/or 24) as deposited may becharacterized by Si_(x)N_(y) layer(s), where x/y may be from 0.76 to1.5, more preferably from 0.8 to 1.4, still more preferably from 0.82 to1.2. Any and/or all of the silicon nitride layers discussed herein maybe doped with other materials such as stainless steel or aluminum incertain example embodiments of this invention. For example, any and/orall silicon nitride layers 3, 14, 24 discussed herein may optionallyinclude from about 0-15% aluminum, more preferably from about 1 to 10%aluminum, in certain example embodiments of this invention. The siliconnitride of layers 3, 14, 24 may be deposited by sputtering a target(s)of Si or SiAl, in an atmosphere having argon and nitrogen gas, incertain embodiments of this invention. Small amounts of oxygen may alsobe provided in certain instances in any or all of the silicon nitridelayers 3, 14, 24.

Absorber layer 15 is preferably of or including niobium zirconium, whichmay be sub-oxided and/or nitrided in certain example embodiments. It hasbeen found that provision of the niobium zirconium based absorber layer15 in a position to split the silicon nitride based layer 14 into twoportions 14 a and 14 b results in improved durability, and allowsdesirable silver glass side/exterior coloration to be achieved incombination with other desirable optical/solar characteristics. Forinstance, when NbZr (or an oxide and/or nitride thereof) is used forabsorber layer 15, various ratios of Nb to Zr in the layer may be usedincluding but not limited to a 50/50 ratio, an 85/15 ratio, or a 90/10ratio. In certain example embodiments of this invention, the Nb/Zr ratioin absorber layer 15 may be from 1/1 to 9.5/1 (more preferably from 2/1to 9/1) in various example embodiments of this invention, such that thelayer 15 preferably contains more Nb than Zr. In certain exampleembodiments, the metal content of absorber layer is from 50-95% Nb, morepreferably from 60-95% Nb, even more preferably from 70-95% Nb (e.g.,with the remainder of the metal content being made up of Zr in certainexample embodiments). While layer 15 consists of, or consistsessentially of, NbZr, NbZrO_(x), or NbZrO_(x)N_(y) in preferredembodiments of this invention, it is possible that other materials maybe present in the layer. For instance, layer 15 may be doped with othermaterials in certain example instances. In certain example embodimentsthe absorber layer 15 may contain from about 0-10% nitrogen, morepreferably from about 1-7% nitrogen. As mentioned herein, it ispreferable that absorber layer 15 is not fully oxided, but is partiallyoxided (sub-oxided) in certain example embodiments of this invention. Incertain example embodiments, absorber layer 15 contains from about 0-40%oxygen, more preferably from 1-35% oxygen, even more preferably from3-30%, even more preferably from 5-20% oxygen (atomic %). The oxygencontent of the layer 15 may be adjusted in order to adjust visibletransmission in certain example instances. In certain exampleembodiments, there is more oxygen than nitrogen in absorber layer 15(regarding atomic %).

While the absorber layer 15 is of NbZr, NbZrO_(x), or NbZrO_(x)N_(y) inpreferred embodiments of this invention, other materials are alsopossible in alternative embodiments. For example, it is possible thatthe absorber layer 15 may be of or include NiCr, NiCrO_(x), orNiCrO_(x)N_(y) in other embodiments of this invention

Infrared (IR) reflecting layers 9 and 19 are preferably substantially orentirely metallic and/or conductive, and may comprise or consistessentially of silver (Ag), gold, or any other suitable IR reflectingmaterial. IR reflecting layers 9 and 19 help allow the coating to havelow-E and/or good solar control characteristics.

Other layer(s) below or above the illustrated coating may also beprovided. Thus, while the layer system or coating is “on” or “supportedby” substrate 1 (directly or indirectly), other layer(s) may be providedtherebetween. Thus, for example, the coating of FIG. 1 may be considered“on” and “supported by” the substrate 1 even if other layer(s) areprovided between layer 3 and substrate 1. Moreover, certain layers ofthe illustrated coating may be removed in certain embodiments, whileothers may be added between the various layers or the various layer(s)may be split with other layer(s) added between the split sections inother embodiments of this invention without departing from the overallspirit of certain embodiments of this invention.

While various thicknesses and materials may be used in layers indifferent embodiments of this invention, example thicknesses andmaterials for the respective layers on the glass substrate 1 in the FIG.1 embodiment are as follows, from the glass substrate outwardly(physical thicknesses recited):

Example Materials/Thicknesses; FIG. 1 Embodiment

Layer Preferred More Glass (1-10 mm thick) Range (Å) Preferred (Å)Example (Å) Si_(x)N_(y) (layer 3) 100-1100 Å 400-1000 Å 674 Å NiCr orNiCrN (layer 7) 5-70 Å 7-30 Å 8 Å Ag (layer 9) 60-170 {acute over (Å)}80-120 Å 151 Å NiCr or NiCrN (layer 11) 5-70 Å 10-35 Å 14 Å Si_(x)N_(y)(layer 14a) 100-700 Å 200-550 Å 430 Å NbZrO_(x) (layer 15) 15-100 Å20-60 Å 32 Å Si_(x)N_(y) (layer 14b) 100-800 Å 250-650 Å 519 Å NiCr orNiCrN (layer 17) 5-70 Å 10-35 Å 15 Å Ag (layer 19) 50-140 {acute over(Å)} 70-110 Å 90 Å NiCr or NiCrN (layer 21) 5-70 Å 7-30 Å 8 Å Si₃N₄(layer 24) 100-500 Å 200-450 Å 329 Å ZrO₂ (layer 27) 20-85 Å 25-55 Å 37Å

The upper portion 14 b of the silicon nitride based layer 14 is at least20 angstroms (more preferably at least 50 angstroms) than is the lowerportion 14 a in certain example embodiments of this invention, althoughthey need not be in alternative embodiments of this invention. Moreover,in certain example embodiments of this invention the absorber layer 15is thinner than both the silver layers 9, 19 (e.g., by at least 20angstroms), and is also thinner than both of the silicon nitride layers14 a, 14 b in certain example embodiments of this invention. In certainexample embodiments of this invention, the absorber layer 15 is at least20 angstroms (Å) thinner than both the silver layers 9, 19, and/or is atleast angstroms 100 angstroms (more preferably at least 200 angstroms,and most preferably at least 250 angstroms) thinner than both of thesilicon nitride layers 14 a, 14 b in certain example embodiments of thisinvention.

In certain example embodiments, the overcoat layer of or includingzirconium oxide and/or zirconium oxynitride 27 is thinner than each ofthe IR reflecting layers 9, 19 comprising silver in the coating 30. Incertain example embodiments of this invention, each of the IR reflectinglayers comprising silver 9 and 19 is at least twice as thick as theovercoat layer 27 or including zirconium oxide and/or zirconiumoxynitride.

In certain example embodiments, the center silicon nitride based layer14 total thickness (14 a+14 b) is thicker than the silicon nitride layer24 thickness, preferably by at least 100 angstroms, more preferably byat least 300 angstroms, and most preferably by at least 400 angstroms.In certain example embodiments, silicon nitride layer 3 is at least 50angstroms thicker (more preferably at least 100 angstroms thicker) thaneach of silicon nitride based layers 14 a and 14 b. Moreover, in certainexample embodiments, each of the silicon nitride based layers 3, 14 and24 is at least two times as thick as the zirconim oxide inclusive layer27, more preferably at least three times as thick, and most preferablyat least four or five times as thick.

Before and/or after any optional heat treatment (HT) such as thermaltempering, in certain example embodiments of this invention coatedarticles according to the FIG. 1 embodiment have color/opticalcharacteristics as follows in Table 2 (measured monolithic and/or in anIG unit). It is noted that subscript “G” stands for glass sidereflective, subscript “T” stands for transmissive, and subscript “F”stands for film side reflective. As is known in the art, glass side (G)means when viewed from the glass side (as opposed to the layer/filmside) of the coated article, i.e., same as when viewed from the exteriorside of a window when viewed from a building exterior when the coatingis on the inner side of the outer glass substrate 1 as shown in FIG. 2for instance. Film side (F) means when viewed from the side of thecoated article on which the coating is provided. The characteristicsbelow in Table 2 are applicable to HT and/or non-HT coated articlesherein. However, HT will cause certain parameters to change such asincreasing visible transmission and lowering sheet resistance (colorvalues will also change due to HT).

TABLE 2 Color/Optical Characteristics (FIG. 1 embodiment monolithic orIG) General Preferred Most Preferred T_(vis) (TY): 15-45% 22-39% 24-35%a*_(T) −10 to +2  −8 to −1 −6.5 to −3.0 b*_(T) −12 to +4  −8 to +1 −6 to0  R_(G)Y(glass side): 23-43% 25-40% 27-35% a*_(G) −6 to +5 −3.5 to +4.0−2.5 to +3.0 b*_(G)  −11 to +3.0  −9 to +1.0 −8.0 to −1.0 R_(F)Y(filmside): <=19% <=17% <=15% a*_(F) −22 to +10 −16 to 0  −14 to −3  b*_(F)−20 to +10 −12 to +5  −9 to 0  R_(s) (Ω/sq): ≤6.0 ≤5.0 ≤4.0 SF [IG]:<=0.27 <=0.25 <=0.21 SHGC [IG]: <=0.27 <=0.25 <=0.23 (or .20)

For purposes of example only, Examples 1-2 below represent differentexample embodiments of this invention.

EXAMPLES

Examples 1 and 2 has the below-listed layer stack on a 5.9 mm thick, 75mm×75 mm, clear matte glass substrate 1 as shown in FIG. 1. The exampleswere measured monolithically, heat treated and measured again after theHT. They were also put into IG window units after HT as shown in FIG. 2,and measured. The silicon nitride layers 3, 14, 24 in each example weredeposited by sputtering a silicon target (doped with about 8% Al) in anatmosphere including argon and nitrogen gas. In the IG window unit, thematte glass substrates 1 and 2 were clear and 5.9 mm thick, and the airgap between the substrates in the IG window unit was 13 mm thick. TheNbZr based absorber layer in each example was deposited by sputteringapproximately 90/10 Nb/Zr magnetron sputtering targets in an atmosphereincluding argon and a small amount of nitrogen and oxygen gas (1.2 ml/kWof oxygen gas was used). Thus, the absorber layer 15 was ofNbZrO_(x)N_(y) in these examples. Layer thicknesses for Examples 1-2were in angstroms (Å) and are as follows, moving from the glasssubstrate 1 outwardly.

TABLE 3 Layer Stacks of Examples 1-2 Layer Glass (5.9 mm thick) Examples1-2 Si₃N₄ (layer 3) 674 Å NiCr (layer 7) 8 Å Ag (layer 9) 151 Å NiCr(layer 11) 14 Å Si_(x)N_(y) (layer 14a) 430 Å NbZrO_(x)N_(y) (layer 15)32 Å Si_(x)N_(y) (layer 14b) 519 Å NiCr (layer 17) 15 Å Ag (layer 19) 90Å NiCr (layer 21) 8 Å Si₃N₄ (layer 24) 329 Å ZrO₂ (layer 27) 37 Å

Measured monolithically before tempering (HT), Examples 1-2 according toembodiments of this invention had the following characteristics with themeasurements being taken from the center of the coated glass article(annealed and non-HT, monolithic) (Ill. C, 2 degree observer).

TABLE 4 Measured Monolithic, annealed (as coated: before tempering)Parameter Ex. 1 Ex. 2 T_(vis) (TY)(transmission ): 28.6% 28.9% a*_(T)−4.2 −4.5 b*_(T) −0.9 −0.3 R_(G)Y(glass side refl. %): 28.9% 29.1%a*_(G): 2.6 2.8 b*_(G): −5.9 −6.6 Glass side refl. color: silver silverR_(F)Y(film side refl. %): 8.7% 9.2% a*_(F): −9.6 −8.7 b*_(F): −2.0 −2.6Sheet Resistance (Ω/sq): 3.0 3.0

It can be seen from Table 4 above that measured monolithically prior toany optional thermal tempering Examples 1-2 were able to realize acombination of (i) desirable silver glass side reflective visible colorincluding high glass side visible reflectance (R_(G)Y), (ii) a low sheetresistance, and (iii) desirable visible transmission.

Measured monolithically after tempering (HT), Examples 1-2 according toembodiments of this invention had the following characteristics (HT,monolithic) (Ill. C, 2 degree observer).

TABLE 5 Measured Monolithic, HT (after tempering) Parameter Ex. 1 Ex. 2T_(vis) (TY)(transmission ): 31.6% 31.8% a*_(T) −3.8 −4.0 b*_(T) −3.9−3.4 R_(G)Y(glass side refl. %): 32.3% 32.6% a*_(G): −1.3 −0.9 b*_(G):−0.4 −0.8 Glass side refl. color: silver silver R_(F)Y(film side refl.%): 7.4% 7.7% a*_(F): −11.9 −10.0 b*_(F): −6.6 −7.9 Sheet Resistance(Ω/sq): 2.6 2.6

It can be seen from Table 5 above that following thermal tempering (HT)Examples 1-2 had a combination of (i) desirable silver glass sidereflective visible color including high glass side visible reflectance,(ii) low sheet resistance, and (iii) desirable visible transmissionvalues.

Measured in an IG window unit as shown in FIG. 2 (with the coating 30 onsurface two) after HT, Examples 1-2 had the following characteristics(tempered, IG unit) (Ill. C, 2 degree observer).

TABLE 6 IG Unit, HT (after tempering) Parameter Ex. 1 Ex. 2 T_(vis)(TY)(transmission ): 28.4% 28.5% a*_(T) −4.8 −4.9 b*_(T) −3.6 −3.1R_(G)Y(glass side refl. %): 33.1% 33.4% a*_(G): −1.4 −1.2 b*_(G): −0.6−1.0 Glass side refl. color: silver silver R_(F)Y(film side refl. %):14.1% 14.3% a*_(F): −7.0 −6.2 b*_(F): −3.6 −4.4 Sheet Resistance (Ω/sq):2.6 2.6 SF (EN410-673 2011): 0.20 0.20 SHGC (NFRC-2001): 0.19 0.19

It can again be seen from the table above, following thermal tempering(HT), IG window units including Examples 1 and 2, respectively, had acombination of: (i) desirable silver glass side/exterior reflectivevisible color including high glass side (exterior) reflectance, (ii) lowsheet resistance, and (iii) desirable visible transmission values, and(v) desirably low SF and SHGC values.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

The invention claimed is:
 1. A coated article including a coatingsupported by a glass substrate and having silver glass side reflectivecolor, the coating comprising: first and second infrared (IR) reflectinglayers comprising silver, the first IR reflecting layer being locatedcloser to the glass substrate than is the second IR reflecting layer; afirst contact layer located over and directly contacting the first IRreflecting layer comprising silver; a dielectric layer comprisingsilicon nitride located over and directly contacting the first contactlayer; wherein the dielectric layer comprising silicon nitride is splitby a splitting absorber layer comprising Nb and Zr, so that thesplitting absorber layer comprising Nb and Zr is located between andcontacting a first portion of the dielectric layer comprising siliconnitride and a second portion of the dielectric layer comprising siliconnitride; a second contact layer located over the layer comprisingsilicon nitride; the second IR reflecting layer comprising silverlocated over and directly contacting the second contact layer; a thirdcontact layer located over and directly contacting the second IRreflecting layer; another dielectric layer comprising silicon nitridelocated over the third contact layer; and wherein the coated article hasa visible transmission of from 15-45%, a glass side visible reflectanceof from 23-43%, a glass side reflective a* value from −6.0 to +5.0, anda glass side reflective b* value from −11.0 to +3.0.
 2. The coatedarticle of claim 1, wherein the absorber layer comprises a suboxide ofNbZr.
 3. The coated article of claim 1, wherein the absorber layerfurther comprises nitrogen.
 4. The coated article of claim 1, whereinthe absorber layer comprises NbZrO_(x)N_(y).
 5. The coated article ofclaim 1, wherein the first and third contact layers comprise Ni and/orCr.
 6. The coated article of claim 1, wherein the second contact layercomprises Ni and Cr.
 7. The coated article of claim 1, furthercomprising a contact layer comprising NiCr located under and directlycontacting the first IR reflecting layer.
 8. The coated article of claim1, wherein the coated article has a glass side visible reflectance offrom 25-40%, a glass side reflective a* value from −3.5 to +4.0, and aglass side reflective b* value from −9.0 to +1.0.
 9. The coated articleof claim 1, wherein the coated article has a glass side reflective a*value from −2.5 to +3.0 and a glass side reflective b* value from −8.0to −1.0.
 10. The coated article of claim 1, wherein the coated articlehas a glass side visible reflectance from 27-35%.
 11. The coated articleof claim 1, wherein the glass side visible reflectance of the coatedarticle is higher than the visible transmission of the coated article.12. The coated article of claim 1, wherein the coated article has atransmissive a* value from −8.0 to −1.0 and a transmissive b* value from−8.0 to +1.0.
 13. The coated article of claim 1, wherein the coatedarticle has a visible transmission from 22-39%.
 14. The coated articleof claim 1, wherein the coating has a sheet resistance no greater than6.0 ohms/square.
 15. The coated article of claim 1, wherein the first IRreflecting layer is at least 20 angstroms thicker than is the second IRreflecting layer.
 16. The coated article of claim 1, wherein the firstIR reflecting layer is at least 40 angstroms thicker than is the secondIR reflecting layer.
 17. The coated article of claim 1, wherein theabsorber layer contains more Nb than Zr.
 18. The coated article of claim1, wherein the absorber layer contains from 3-30% oxygen (atomic %). 19.The coated article of claim 1, wherein a metal content of the absorberlayer is from 70-95% Nb.
 20. The coated article of claim 1, furthercomprising a base layer comprising silicon nitride located between theglass substrate and the first IR reflecting layer.
 21. The coatedarticle of claim 1, wherein the absorber layer has a thickness of from15-100 angstroms.
 22. The coated article of claim 1, wherein theabsorber layer has a thickness of from 20-60 angstroms.
 23. The coatedarticle of claim 1, wherein the absorber layer consists essentially ofNbZrO_(x)N_(y).
 24. The coated article of claim 1, wherein the absorberlayer is thinner than both of the IR reflecting layers comprisingsilver.
 25. The coated article of claim 1, further comprising anovercoat layer comprising zirconium oxide located over and directlycontacting the another dielectric layer comprising silicon nitride. 26.The coated article of claim 1, wherein the first contact layer comprisesNiCr and is substantially metallic or metallic, and contains no morethan 5% (atomic %) oxygen.
 27. The coated article of claim 1, whereinthe first, second, and third contact layers contain no more than 5%(atomic %) oxygen.
 28. The coated article of claim 1, wherein the coatedarticle is thermally tempered.
 29. The coated article of claim 1,wherein the coated article has a film side reflective b* value from −9to
 0. 30. A IG window unit including the coated article of claim 1, andanother glass substrate which is coupled to said coated article, whereinthe IG window unit has an SF value no greater than 0.27 and an SHGCvalue no greater than 0.27, and wherein the glass side visiblereflectance is as if viewed from an exterior of a building in which theIG window unit is, or is to be, provided.
 31. A IG window unit includingthe coated article of claim 1, and another glass substrate which iscoupled to said coated article, wherein the IG window unit has an SFvalue no greater than 0.25 and an SHGC value no greater than 0.25.
 32. AIG window unit including the coated article of claim 1, and anotherglass substrate which is coupled to said coated article, wherein the IGwindow unit has an SF value no greater than 0.21 and an SHGC value nogreater than 0.20.
 33. A coated article including a coating supported bya glass substrate and having silver glass side reflective color, thecoating comprising: first and second infrared (IR) reflecting layerscomprising silver, the first IR reflecting layer being located closer tothe glass substrate than is the second IR reflecting layer; a firstcontact layer located over and directly contacting the first IRreflecting layer comprising silver; a dielectric layer comprisingsilicon nitride located over the first contact layer; wherein thedielectric layer comprising silicon nitride is split by a splittingabsorber layer, so that the splitting absorber layer is located betweenand contacting a first portion of the dielectric layer comprisingsilicon nitride and a second portion of the dielectric layer comprisingsilicon nitride; a second contact layer located over the layercomprising silicon nitride; the second IR reflecting layer comprisingsilver located over and directly contacting the second contact layer; athird contact layer located over and directly contacting the second IRreflecting layer; another dielectric layer comprising silicon nitridelocated over the third contact layer; wherein the coated article has avisible transmission of from 20-45%; and wherein the coated article hasa glass side visible reflectance of from 23-43%, a glass side reflectivea* value from −6.0 to +5.0, and a glass side reflective b* value from−11.0 to +3.0.
 34. A coated article including a coating supported by aglass substrate, the coating comprising: first and second infrared (IR)reflecting layers comprising silver, the first IR reflecting layer beinglocated closer to the glass substrate than is the second IR reflectinglayer; a first contact layer located over and directly contacting thefirst IR reflecting layer comprising silver; a dielectric layercomprising silicon nitride located over the first contact layer; whereinthe dielectric layer comprising silicon nitride is split by a splittinglayer comprising NbZrO_(x)N_(y), so that the splitting layer comprisingNbZrO_(x)N_(y) is located between and contacting a first portion of thedielectric layer comprising silicon nitride and a second portion of thedielectric layer comprising silicon nitride; a second contact layerlocated over the layer comprising silicon nitride; the second IRreflecting layer comprising silver located over and directly contactingthe second contact layer; a third contact layer located over anddirectly contacting the second IR reflecting layer; and wherein thecoated article has a visible transmission of from 15-45%, a glass sidevisible reflectance of from 23-43%, a glass side reflective a* valuefrom −6.0 to +5.0.
 35. The coated articled of claim 34, wherein thecoated article has a glass side reflective a* value from −3.5 to +4.0and a glass side reflective b* value from −9.0 to +1.0.